Chips and grinding sludge produced when an iron-base metal such as bearing steel and carburizing steel is ground or polished are recovered as a flocculent (fibrous) aggregate including a grinding fluid which contains water and oil, and abrasive grains. Since this flocculent aggregate contains a large amount of pure iron, a technique for reusing this as a steel making raw material has been proposed from the viewpoints of environmental protection and resource saving. For example, as shown in Japanese Patent Laid-Open No. 2002-129248, a compact, which is obtained by compression molding a flocculent aggregate, is impregnated with a solidifying auxiliary substance (hardening fluid), and then drying treatment is performed, by which briquettes are manufactured. Then, the manufactured briquettes are recovered by a steel maker, being remelted, and are recycled.
As an apparatus for manufacturing such briquettes, the apparatus disclosed, for example, in Japanese Registered Utility Model No. 3009829 has been known conventionally. This apparatus includes a screw for feeding a charged flocculent aggregate into a mold (molding chamber) on the lower side and a pressing machine for compression molding the aggregate fed into the mold.
The mold of the pressing machine described in Japanese Registered Utility Model No. 3009829 is firmly fixed to an apparatus frame, and the flocculent aggregate, which is the material for briquettes, is compressed in the cavity of this mold. The compressed aggregate spreads in the cavity to the side in the direction perpendicular to the pressing direction of the pressing machine, and is pushed strongly against the inner peripheral surface of the mold. Therefore, the aggregate is compressed while producing a great frictional resistance (sliding force) between the aggregate and the inner peripheral surface of the mold. For this reason, the pressing force of the pressing machine requires a force for withstanding this frictional resistance in addition to a force for actually compressing the aggregate, which presents a problem in that the efficiency is poor and hence a pressing machine with a high capacity is needed.
The flocculent aggregate, which is the material for briquettes, contains a large amount of water, so that in order to obtain recyclable briquettes, the briquettes must be dried sufficiently. The reason for this is that if briquettes from which water is removed insufficiently are charged into a blast furnace of a steel maker as they are, bumping (water vapor explosion) may be generated by the water in the briquettes.
A method is conceivable in which water is removed by applying a high compressive load to the flocculent aggregate, which is the material for briquettes, using the pressing machine described in Japanese Registered Utility Model No. 3009829. However, even if the aggregate is compressed by increasing the compressive load, water drainage from the mold is poor, so that it is difficult to remove water sufficiently. Further, since the water drainage is poor, the loss of pressing force of the pressing machine occurs. For the conventional apparatus, even if the compressive load is increased, the removal of water has a limit, and thus a problem of wastefully increasing capability (capacity) of the pressing machine arises.
It is also conceivable that dried briquettes are obtained by separately installing a drier, in addition to the apparatus described in Japanese Registered Utility Model No. 3009829, in order to sufficiently remove water. That is to say, it is conceivable to perform treatment by arranging the pressing machine for performing compression molding and the drier for performing drying independently in one plane in a mill, and connect the machines to each other by separately installing a conveyor or by manually.
However, in the case where each machines are arranged independently in one plane in a mill in this manner, the installation area (occupied area) of the whole facility becomes very large. Also, a problem arises in that work for carrying briquettes from machine to machine manually is troublesome and much manpower is required.